The L250 is the most
advanced loudspeaker JBL has ever built for the home. From the shape of the
enclosure to the design of the level
controls. JBL has spared no effort. Overlooked no performance factor necessary
to building the most accurate loudspeaker possible.
The L250 will sound
as good as your other equipment will
allow. Frequency response is nearly ruler-flat over the whole audible
bandwidth. Distortion is held to levels more typical of fine electronics than
of loudspeakers. JBL engineers paid particular attention to stereo imaging,
so that it is precise, stable and
three-dimensional.
Form follows,
function in the L250's enclosure The
asymetrical shape minimizes diffraction effects, as do the rounded edges. The
sloping front baffle puts the drivers in correct time and phase relationship as
well. To further assure s stable image, the L250's are designed in
mirror-imaged pairs.
An advanced, highly
refined version of JBL's high resolution dividing network contributes greatly
to the excellent performance. The network is a first-order design with 6dB per
octave slopes for the smoothest blending of the drivers. Conjugate circuits level
the impedance of each driver, so that actual operation approaches the
theoretical ideal.
Instead of
conventional level controls, the L250 uses fixed-value, stepped attenuators to
give the performance advantages of hard wire while still allowing level
adjustments, which are made via high-current bus bars.
The L250 is finished
in oiled walnut venner. Four other finishes and six grille colors are available
by special order.
Symmetrical Field
Geometry
The low frequency
driver of the Lseries loudspeakers incorporate JBL's unique Symmetrical Field
Geometry (SFG) magnetic structures. There are two innovations in the SFG
design. One is the symmetrical magnetic field around the voice coil gap, which
reduces second harmonic distortion below 100Hz. Conventional Designs have an
asymmetrical field around the gap, so that the interaction of the field and the
voice coil is non linear. The second SFG
innovation is the Flux Stabilizing Ring encircling the pole piece. This reduces
the second harmonic distortion above 100Hz. Because the low frequency drivers
of JBL loudspeakers have bandwidths extending well above 100Hz, SFG results in
both cleaner bass and cleaner midrange.
High Resolution
Dividing Network
Most dividing
networks blur musical transients because the large capacitors necessary for
high power handling introduce a slight time lag between the input and output
signal. (This is called hysteresis.) To improve transient resolution, JBL
engineers incorporated circuitry more typical of active high frequency
electronics. Small, highly linear 'Bypass" capacitors, wired in parallel
with the larger capacitors, enable the network to pass transient waveforms
unaltered. These high resolution frequency dividing networks are found in all
JBL L Series loudspeaker systems.
Specifications
System: Four-way
floor-standing system
Max. Amplifier
Power: 400 watts per channel
Nominal
Impedance: 8 ohms
Crossover
Frequencies: 400 Hz, 1,500 Hz, 5,000 Hz
Sensitivity: 90 dB SPL
Low Frequency Driver
Nominal
Diameter: 360 mm (14")
Voice Coil: 100 mm (4")
Magnetic
Assembly: Edgewound copper
Weight: 8,5 kg (18-5/8 lb)
Lower Midrange
Driver
Nominal
Diameter: 200 mm (8")
Voice Coil: 50 mm (2")
Magnetic
Assembly: Copper
Weight: 2,7 kg (6 lb)
Midrange Driver
Nominal
Diameter: 130 mm (5")
Voice Coil:22 mm
(7/8")
Magnetic
Assembly: Edgewound copper
Weight: 0,74 kg (1-5/8 lb)
High Frequency Dome
Radiator
Nominal
Diameter: 25 mm (1")
Voice Coil: 25 mm (1")
Magnetic
Assembly: Copper
Weight: 0,9 kg (2 lb)
Finish: Transparent Black Stain, Indian rosewood,
Macassar ebony, White oak
Grille Colors: Brown, Blue, Black, Rust, Tan, Maroon
Dimensions
(H x W x D): 1321 x 572 x 362 mm
(52" x 22½" x 14¼")
Weight: 68 kg (150 lb)